Previous edge enhancement methods use a max-min refinement search circuit to detect maximum and minimum turning points closest to the center of the process window and use these turning points to determine values and locations of maximum and minimum pixels of the edge. With these determined maximum and minimum pixels, the input pixel is enhanced by a predefined enhancement curve controlled by a selective edge control.
In these methods, the maximum and minimum pixels of the edge are determined by the turning points. The turning points are detected by sign of the first derivative of three neighbor pixels. However, the use of turning point detection is sensitive to noise and will create a “striped noise” artifact, which is an unexpected striped noise observable between two narrow edges, in the enhanced result.